The tech is removing the EEG electrodes from Dan, including the one above his right eye, as seen in close-up. But, in the next medium shot, the electrode above his right eye is still in place.
Although most of the officers are wearing the Vietnam Campaign and Vietnam Service ribbons, none of them wears a patch on their right shoulder depicting the unit they served with in Vietnam. The wearing of such "combat patches" is customary in the U.S. Army.
The med-evac helicopter used in this film was Korean War vintage and completely out of date. This film is set in the early 1970's. The UH-1 helicopter had been flying for the United States Army since 1959.
The helicopter seen in this film is the Bell H-13 Souix and while it was state of the art in Korea, it could only carry two casualties on exterior stretchers. This helicopter was probably chosen for the visual of George C. Scott's body being air-lifted out on the outside stretchers.
The helicopter Col. Franklin arrives on has an obvious civilian registration number on its tail boom - N1406W - but has been painted to resemble a U.S. Army helicopter.
When Dan shoots the alarm bell twice, no holes or damage appears on the bell or anywhere around it, but it pops off the wall anyways.
When Dan shoots through the windshield of the van, the damage to the glass does not align with where the barrel of the gun is pointed, nor does it appear exactly when the gun is fired. Also note the soot rings on the inside of the windshield from the blanks used.
When Dan opens the door to the hospital's morgue, it is pitch dark inside, yet he immediately knows where to reach for the light switch and turns the lights on.